1. Field of the Invention
The present invention relates, in general, to a multi system type air conditioning apparatus capable of air conditioning a plurality of rooms.
2. Description of the Related Art
In general, a multi system type air conditioner is equipped with a single outdoor unit provided with at least a compressor and outdoor heat exchanger, and a plurality of indoor units each having at least one indoor heat exchanger. These indoor units, being connected to the outdoor unit, are capable of cooling operation and heating operation.
An example of this technique is described in detail in Japanese Patent Publication (Kokoku) Nos. 61-45145/1986 and 64-57061/1989.
Furthermore, in U.S. Pat. No. 4,878,357, Sekigami et al. shows a multiroom air conditioning apparatus that includes a plurality of outdoor heat exchangers for carrying out simultaneous room cooling and heating operations.
In such an air conditioner, during heating operation, the outdoor heat exchanger operates as an evaporator. Frost gradually sticks to the surface of the outdoor heat exchanger, and a lowering of the heating capacity occurs. It is conventional to melt this frost on the outdoor heat exchanger by allowing a high temperature refrigerant discharged from the compressor to flow to the outdoor heat exchanger. This can be done either periodically as determined by a timer etc., or as required, based on the temperature of the outdoor heat exchanger.
However, when defrosting is carried out by supplying high temperature refrigerant as described above, the indoor heat exchangers act as evaporators. As a result cold air is discharged into the rooms.